From patchwork Mon Nov 27 16:08:37 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beata Michalska X-Patchwork-Id: 747764 Authentication-Results: smtp.subspace.kernel.org; dkim=none Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 091F599; Mon, 27 Nov 2023 08:09:07 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 77779165C; Mon, 27 Nov 2023 08:09:54 -0800 (PST) Received: from e125905.cambridge.arm.com (e125905.cambridge.arm.com [10.1.194.73]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 26D123F6C4; Mon, 27 Nov 2023 08:09:05 -0800 (PST) From: Beata Michalska To: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, sumitg@nvidia.com Cc: sudeep.holla@arm.covm, will@kernel.org, catalin.marinas@arm.com, viresh.kumar@linaro.org, rafael@kernel.org, ionela.voinescu@arm.com, yang@os.amperecomputing.com, linux-tegra@vger.kernel.org, Sudeep Holla Subject: [PATCH v2 1/2] arm64: Provide an AMU-based version of arch_freq_get_on_cpu Date: Mon, 27 Nov 2023 16:08:37 +0000 Message-Id: <20231127160838.1403404-2-beata.michalska@arm.com> In-Reply-To: <20231127160838.1403404-1-beata.michalska@arm.com> References: <20231127160838.1403404-1-beata.michalska@arm.com> Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 With the Frequency Invariance Engine (FIE) being already wired up with sched tick and making use of relevant (core counter and constant counter) AMU counters, getting the current frequency for a given CPU on supported platforms, can be achieved by utilizing the frequency scale factor which reflects an average CPU frequency for the last tick period length. Suggested-by: Ionela Voinescu Signed-off-by: Beata Michalska Reviewed-by: Sudeep Holla --- Notes: Due to [1], if merged, there might be a need to modify the patch to accommodate changes [1] introduces: freq = cpufreq_get_hw_max_freq(cpu) >> SCHED_CAPACITY_SHIFT to freq = per_cpu(capacity_freq_ref, cpu); >> SCHED_CAPACITY_SHIFT [1] https://lore.kernel.org/linux-arm-kernel/20231121154349.GA1938@willie-the-truck/T/#mcb018d076dbce6f60ed2779634a9b6ffe622641e arch/arm64/kernel/topology.c | 39 ++++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c index 615c1a20129f..ae2445f6e7da 100644 --- a/arch/arm64/kernel/topology.c +++ b/arch/arm64/kernel/topology.c @@ -17,6 +17,7 @@ #include #include #include +#include #include #include @@ -186,6 +187,44 @@ static void amu_scale_freq_tick(void) this_cpu_write(arch_freq_scale, (unsigned long)scale); } +unsigned int arch_freq_get_on_cpu(int cpu) +{ + unsigned int freq; + u64 scale; + + if (!cpumask_test_cpu(cpu, amu_fie_cpus)) + return 0; + + /* + * For those CPUs that are in full dynticks mode, try an alternative + * source for the counters (and thus freq scale), + * if available for given policy + */ + if (!housekeeping_cpu(cpu, HK_TYPE_TICK)) { + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + int ref_cpu = nr_cpu_ids; + + if (cpumask_intersects(housekeeping_cpumask(HK_TYPE_TICK), + policy->cpus)) + ref_cpu = cpumask_nth_and(cpu, policy->cpus, + housekeeping_cpumask(HK_TYPE_TICK)); + cpufreq_cpu_put(policy); + if (ref_cpu >= nr_cpu_ids) + return 0; + cpu = ref_cpu; + } + + /* + * Reversed computation to the one used to determine + * the arch_freq_scale value + * (see amu_scale_freq_tick for details) + */ + scale = per_cpu(arch_freq_scale, cpu); + freq = cpufreq_get_hw_max_freq(cpu) >> SCHED_CAPACITY_SHIFT; + freq *= scale; + return freq; +} + static struct scale_freq_data amu_sfd = { .source = SCALE_FREQ_SOURCE_ARCH, .set_freq_scale = amu_scale_freq_tick,